Acute myeloid leukemia (AML) is considered to be a malignancy that is intrinsically resistant to methotrexate (MTX). As compared to acute lymphoblastic leukemia (ALL) blasts, AML blasts, except those of acute monocytic leukemia (AML-M(5)), form fewer amounts of long chain polyglutamate of MTX (MTXPG), when incubated with MTX, thus providing an explanation for their lack of responsiveness to MTX. To explore the novel approach of treatment in patients with AML-M(5), the U937 cell line, which has the monocytic characters, was used. Cell growth inhibition was mearsured by XTT assay after 24 and 48 hours in the continuous presence of various concentrations of MTX ranging from 1 nmol/L to 100 micro mol/L. After 24 hours MTX treatment, the IC(50) value for U937 cells was 0.04 micro mol/L. After 48 hours treatment, the IC(50) was 0.037 micro mol/L and IC(90) was 0.39 micro mol/L. To understand the mechanism of MTX cytotoxicity, the process of cell death was analyzed. A variety of assays, including trypan blue exclusion, flow cytometry, light microscopy (Wright's staining) and DNA fragment electrophoresis, were performed. There were no significant apoptotie changes after shorter exposure of MTX (4 and 6 hours). After 8 hours at various concentrations of MTX treatment ranging from 5 nmol/L to 10 micro mol/L, the percentage of the cells in the pre-G(1) (apoptotic) was 3.2% at 0.1 micro mol/L and it reached a peak of 18.2% at 5.0 micro mol/L. The DNA synthesis in S-phase was inhibited from 41.2% (0.01 micro mol/L) to 19.1% (10 micro mol/L). DNA ladder band, a feature of apoptosis, was observed. The arrest of cell growth and apoptotic properties induced by MTX have lead to its evaluation as a potentially therapeutic agent in the treatment of AML-M(5).

Objective To investigate the mediating effects of neurotic personality between parental rearing patterns and depressive symptom.Methods Using multistage sampling method,982 town middle-school students were surveyed by the Symptom Checklist 90(SCL-90),the Egna Minnen av Barndoms Uppfostran (EMBU),the Eysenck Personality Questionnaire (EPQ).Correlation and regression analysis,mediating effect test,and structural equation model were constructed.Results ①)Depressive symptom (D) (1.73 ± 0.72) was significantly associated with Neurotic personality (N) (51.50± 11.37) and parental rearing patterns (r=-0.138-0.582,P＜0.01).②N,mother's rejection and deny(M3),father's emotional warmth and understanding(F1),father's over-protection(F6) had a direct effect on D,which can explain 41.6％ of the variance.F1,F6,mother's over-interference and over-protection(M2),M3 had a direct effect on N,which can explain 15.3％ of the variance.The mediating effect of N between F1,F6,M2 and D were significant(95％CI =-0.212--0.069,-0.351--0.233,0.414-0.480).③The explanation for D was 41.3％.N had completely mediating effect between M2 and depressive symptom.N had partial mediating effect between F1,F6 and D,and the proportion was 43.6％ and 49.1％.Conclusion Neurotic personality plays a mediating role between parental rearing patterns and depressive symptom in middle-school students.

PURPOSE: The maximum width between the mesial and distal labial transitional line angles, described as “esthetic width” herein, could significantly influence the visual perception of the teeth and smile. This study aimed to conduct biometric research on esthetic width and to explore whether regular distribution exists in the esthetic width of human teeth. MATERIALS AND METHODS: A total of 4,264 maxillary and mandibular anterior teeth were measured using the Geomagic studio software program. The proportions of maxillary to mandibular homonymous teeth and proportions between the adjacent teeth were calculated. Bilateral symmetry and the correlation between the esthetic and mesiodistal widths were both accounted for during the measurement procedures. RESULTS: The mean esthetic widths were 6.773 ± 0.518 mm and 4.329 ± 0.331 mm for maxillary and mandibular central incisors, respectively, 5.451 ± 0.487 mm and 5.008 ± 0.351 mm for maxillary and mandibular lateral incisors, respectively, and 3.340 ± 0.353 mm and 5.958 ± 0.415 mm for maxillary and mandibular canines, respectively. Except for the mandibular canines, no significant difference in esthetic width was found among homonymous teeth from the same jaw. A high linear correlation was found between the esthetic and mesiodistal widths of the same tooth, except for the maxillary canines. Esthetic width proportions among different tooth categories showed some regular patterns, which were similar to those of the mesiodistal width. CONCLUSION Esthetic width is regularly distributed among the teeth in the Chinese population. This could provide an important reference for anterior dental restorations and dimension recovery in esthetic reconstruction of anterior teeth.

The CRISPR-Cas9 system is composed of a clustered regularly interspaced short palindromic repeat (CRISPR) and its associated proteins, which are widely present in bacteria and archaea, serving as a specific immune protection against viral and phage secondary infections. CRISPR-Cas9 technology is the third generation of targeted genome editing technologies following zinc finger nucleases (ZFNs) and transcription activator like effector nucleases (TALENs). The CRISPR-Cas9 technology is now widely used in various fields. Firstly, this article introduces the generation, working mechanism and advantages of CRISPR-Cas9 technology; secondly, it reviews the applications of CRISPR-Cas9 technology in gene knockout, gene knock-in, gene regulation and genome in breeding and domestication of important food crops such as rice, wheat, maize, soybean and potato. Finally, the article summarizes the current problems and challenges encountered by CRISPR-Cas9 technology and prospects future development and application of CRISPR-Cas9 technology.
Gene Editing ; CRISPR-Cas Systems/genetics* ; Plant Breeding ; Crops, Agricultural/genetics* ; Technology